This page shows what was measured, who it was measured in, and what that does not settle.
What Caplacizumab does in the body
Stopping the microscopic clots of acquired TTP by cutting the tether that platelets are being dragged onto
In this disease, long sticky strings of a protein called von Willebrand factor stay uncut in the bloodstream, and platelets are pulled onto them and consumed until almost none are left. Caplacizumab is a very small antibody fragment with two identical grippers joined by a short linker. It clamps onto the exact patch of the string that platelets stick to, so the platelets simply flow past. It does not repair the missing enzyme or remove the antibodies causing the problem; it holds the line while other treatments do that.
What happened in people
Composite of TTP-related death, recurrence or thromboembolic event during treatment in 12% against 49% (p<0.001)
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
The recorded finding that sits closest to something a person would notice. Written into the record, not signed off, and it carries no population or interval.
HERCULES — caplacizumab in acquired thrombotic thrombocytopenic purpura (NCT02553317) · a recorded source, not a stored snapshot
The limit that matters most
That the drug reduces mortality — four deaths occurred across 145 randomised patients in the pivotal trial and six across both trials, which cannot support any survival claim
Where it acts
The lumen of small blood vessels, on the ultralarge von Willebrand factor strings anchored to damaged endothelium
Kind of result
Living longer, or avoiding a major event
Supervision
Professional supervision is normally required. It is a prescription or clinician-administered medicine where it is approved.
What the registries record it as
The substance registry classes this as protein.
FDA substance registry · 2R27AB6766 · read 2026-08-29
Where each sentence above came from
No recorded sentence describes the change this makes in a way that stands on its own. The page opens with what it is taken for instead, and the recorded explanation follows below.
Shown as the opening line on this page.
A limit recorded against this substance. Not signed off as a reviewed claim.
The four opening statements run to 125 words.
Words this page uses
Four words worth knowing first
Chosen from what this page shows, with each one explained before the word it depends on.
Comparator
A comparator is whatever the treatment was measured against.
A picture of it, and where the picture fails
It is like the other runner in a race.
Where that stops being true. A race has one winner. A study can show both arms improved.
What people get wrong. Results are read without asking what the other group got. Beating nothing is not beating a treatment.
The control condition against which the experimental intervention is assessed.
Randomisation
Randomisation means chance decides who gets which treatment.
A picture of it, and where the picture fails
It is like a coin toss deciding the groups.
Where that stops being true. A coin toss is fair once. Fairness here comes from doing it for everyone.
What people get wrong. It is thought to make groups identical. It makes them similar on average, including on things nobody measured.
Allocation of participants to arms by a chance process, so that unmeasured factors are balanced in expectation.
Absolute difference
An absolute difference is how many more people in a hundred were affected.
A picture of it, and where the picture fails
It is like counting heads in two rooms of a hundred.
Where that stops being true. Heads are easy to count. Study results carry a margin of error too.
What people get wrong. It is confused with a percentage change, which can look far larger.
The arithmetic difference in event rates between arms.
Confidence interval
A confidence interval is the range the true answer is likely to sit in.
A picture of it, and where the picture fails
It is like a weather forecast giving a range rather than one number.
Where that stops being true. A forecast range covers tomorrow. This one covers what the study could resolve.
What people get wrong. The middle number is read as the answer. A range crossing zero means no change is still possible.
An interval estimate that would contain the true parameter in a stated proportion of repeated studies.
What happened in people◇Read from sources, not yet reviewed
What happened in people
Each card is one study: the exact question it asked, who was in it, and whether it showed what it set out to show.
Time to normalisation of the platelet count, with discontinuation of daily plasma exchange within 5 days thereafter
✓ The study showed what it set out to show
Who was studied
HERCULES (NCT02553317) — caplacizumab in acquired thrombotic thrombocytopenic purpura
Median 2.69 days (95% CI 1.89 to 2.83) versus 2.88 days (95% CI 2.68 to 3.56), p = 0.01; rate ratio 1.55 for platelet normalisation
Repeated elsewhere
Partially Replicated
What this does not prove. Meeting one endpoint in one population does not carry to other goals or other people.
The limits of this study, and where it came from
Main limit. The primary endpoint difference is a median of about four and a half hours. Mucocutaneous bleeding occurred in 65% versus 48%. Three placebo patients died during the treatment period and one caplacizumab patient died of cerebral ischaemia afterwards — four deaths in total, far too few to say anything about survival.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Intravenous loading dose followed by daily subcutaneous injection
Interval reported. 95% CI 1
Written into the record, not signed off as a reviewed claim.
HERCULES — caplacizumab in acquired thrombotic thrombocytopenic purpura (NCT02553317) · a recorded source, not a stored snapshot
TITAN — phase 2 caplacizumab in acquired thrombotic thrombocytopenic purpura (NCT01151423) · a recorded source, not a stored snapshot
Composite of TTP-related death, recurrence of TTP, or a thromboembolic event during the treatment period
✓ The study showed what it set out to show
Who was studied
HERCULES key secondary composite endpoint
How many people
145
Study design
Prespecified key secondary analysis within the phase 3 trial
Compared against
Not recorded for this study
Kind of result
Living longer, or avoiding a major event
What was found
12% versus 49%, a 74% relative reduction, p < 0.001
Repeated elsewhere
Partially Replicated
What this does not prove. Meeting one endpoint in one population does not carry to other goals or other people.
The limits of this study, and where it came from
Main limit. The composite is dominated by recurrence, its most frequent component; recurrence alone was 12% versus 38%. Reading the composite as a mortality effect is not supported by the four deaths that occurred.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Intravenous loading dose followed by daily subcutaneous injection
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
HERCULES — caplacizumab in acquired thrombotic thrombocytopenic purpura (NCT02553317) · a recorded source, not a stored snapshot
TITAN — phase 2 caplacizumab in acquired thrombotic thrombocytopenic purpura (NCT01151423) · a recorded source, not a stored snapshot
Time to response, defined as confirmed normalisation of the platelet count
✓ The study showed what it set out to show
Who was studied
TITAN (NCT01151423) — phase 2 caplacizumab in acquired TTP
How many people
75
Study design
Phase 2 randomised controlled study
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
39% reduction in median time to response, p = 0.005
Repeated elsewhere
Replicated
What this does not prove. Meeting one endpoint in one population does not carry to other goals or other people.
The limits of this study, and where it came from
Main limit. Eight caplacizumab patients relapsed in the first month after stopping the drug, seven with ADAMTS13 activity still below 10%. Bleeding-related adverse events occurred in 54% versus 38%. Two placebo patients died and none on caplacizumab.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Intravenous loading dose followed by daily subcutaneous injection
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
HERCULES — caplacizumab in acquired thrombotic thrombocytopenic purpura (NCT02553317) · a recorded source, not a stored snapshot
TITAN — phase 2 caplacizumab in acquired thrombotic thrombocytopenic purpura (NCT01151423) · a recorded source, not a stored snapshot
What we know
RNAWiki holds 3 written-up human studies for this substance, each with the question it asked.
How we know it
Each card names the study, the number of people and what the study set out to measure.
What this does not prove
These summaries were written by a person and have not been signed off as reviewed claims.
Why it matters
A study that failed is as informative as one that worked, and both are here.
What we still do not know
No reviewed claim exists, so no exact population, effect size or interval is published yet.
What it changes in the body◇Read from sources, not yet reviewed
The path through the body
From what a person takes to what changes. A solid line is a step measured in people. A dashed line is a step nobody has measured that way.
Start
Caplacizumab
What a person takes: Intravenous loading dose followed by daily subcutaneous injection.
The measurement behind this step
A lyophilised powder in single-dose vials delivering 11 mg, reconstituted with 1 mL of sterile water. The first dose is given intravenously for immediate effect and subsequent doses subcutaneously once daily, continuing through plasma exchange and for a period afterwards. The daily schedule is a direct consequence of the molecule’s size: at 28 kDa it is cleared renally rather than recycled like a full antibody.
Getting in
A loading dose into a vein, then a daily injection under the skin
The first dose goes into a vein so it works immediately; after that it is a small daily injection under the skin, continued for a period after plasma exchange finishes.
──Measured in people. Written by a person from the study named beside the step. Not signed off as a reviewed claim.
The measurement behind this step
In the pivotal trial the regimen was a 10 mg intravenous loading bolus followed by 10 mg daily subcutaneously during plasma exchange and for 30 days afterwards. Supplied as a lyophilised powder in single-dose vials delivering 11 mg, reconstituted with 1 mL of sterile water to 11 mg/mL at pH 6.5.
HERCULES — caplacizumab in acquired thrombotic thrombocytopenic purpura (NCT02553317) · a recorded source, not a stored snapshot
Reaching the cell
A fragment small enough to leave through the kidneys
At about a fifth the size of an ordinary antibody, it moves quickly into the bloodstream from under the skin and is cleared quickly too — which is why it has to be given every day.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
Approximately 28 kDa, below the renal filtration threshold that keeps full antibodies in circulation for weeks. It has no Fc domain and so no neonatal Fc receptor recycling, which is what makes daily dosing necessary and also what makes the effect wear off quickly once stopped.
HERCULES — caplacizumab in acquired thrombotic thrombocytopenic purpura (NCT02553317) · a recorded source, not a stored snapshot
What it acts on
It clamps the exact patch platelets stick to
Von Willebrand factor grips platelets through one specific region. The drug has two identical grippers that cover that region, so the platelet has nothing to hold onto.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
The label states that caplacizumab targets the A1 domain of von Willebrand factor and inhibits the interaction between the factor and platelets, reducing both adhesion and consumption. The A1 domain engages platelet glycoprotein Ib. Bivalency through the three-alanine linker gives avidity that a single domain would not achieve.
HERCULES — caplacizumab in acquired thrombotic thrombocytopenic purpura (NCT02553317) · a recorded source, not a stored snapshot
The change it makes
Platelets stop being dragged out of circulation
The uncut strings are still there, still stretched across small vessels — but nothing sticks to them. Platelets that were being consumed by the thousand simply flow past.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
The A1 domain is only exposed when the multimer is stretched by shear, which is why the disease manifests in the microvasculature and why blockade of this one domain is enough to stop the whole process. The uncleaved ultralarge multimers persist, and so does the ADAMTS13 deficiency that produced them.
HERCULES — caplacizumab in acquired thrombotic thrombocytopenic purpura (NCT02553317) · a recorded source, not a stored snapshot
What that does for a person
The platelet count recovers — a few hours sooner than without it
Counts come back to normal in about 2.7 days rather than about 2.9. The bigger differences are in what happens next: fewer relapses, fewer plasma exchange sessions, shorter hospital stay.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
Median time to platelet normalisation 2.69 days (95% CI 1.89 to 2.83) against 2.88 days (95% CI 2.68 to 3.56), p=0.01. The composite of TTP-related death, recurrence or thromboembolic event during treatment 12% against 49% (p<0.001), and recurrence at any point 12% against 38% (p<0.001), with no refractory disease on caplacizumab against three cases on placebo.
HERCULES — caplacizumab in acquired thrombotic thrombocytopenic purpura (NCT02553317) · a recorded source, not a stored snapshot
What that does for a person
Stop too early and the disease is still there, waiting
Because the drug never touches the missing enzyme or the antibody destroying it, withdrawing it before the immune problem is fixed simply uncovers the disease again.
──Measured in people. Written by a person from the study named beside the step. Not signed off as a reviewed claim.
The measurement behind this step
In TITAN, eight caplacizumab patients relapsed within a month of stopping, seven of them with ADAMTS13 activity still below 10%, which the investigators attribute to unresolved autoimmune activity. Practice now monitors ADAMTS13 recovery before withdrawal — a treatment rule derived from a trial finding rather than from the label.
HERCULES — caplacizumab in acquired thrombotic thrombocytopenic purpura (NCT02553317) · a recorded source, not a stored snapshot
No suggested links are held for this record, so nothing is hidden from this path.
What we know
The record describes 6 steps from taking it to an effect in a person.
How we know it
Each step names the study behind it in the technical detail beside it.
What this does not prove
A change inside the body is a reason to look. It is not a result in a person.
Why it matters
A reader can see exactly where the chain stops being measured in people.
What we still do not know
No reviewed claim binds any of these steps to a named population.
What is missing or unclear◇Read from sources, not yet reviewed
Were people like you studied?
RNAWiki cannot tell whether a study fits you. It can show who was in it, and where the result stops carrying.
Who was studied
People similar to this profile were included.
Adults and adolescents in hospital with an acute episode of acquired TTP, given alongside plasma exchange and immunosuppression, and continued for a period after exchange stops.
Who is missing from the studies
Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.
What the label states about particular groups
On pediatric, the label states: “The safety and effectiveness of CABLIVI in pediatric patients less than 12 years of age have not been established.”
US prescribing information · 2348f06e-8004-4040-832e-e9e86a39f905 · read 2026-08-30
On older people, the label states: “Clinical studies of CABLIVI did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects.”
US prescribing information · 2348f06e-8004-4040-832e-e9e86a39f905 · read 2026-08-30
On people who are pregnant, the label states: “Risk Summary There are no available data on CABLIVI use in pregnant women to inform a drug-associated risk of major birth defects and miscarriage.”
US prescribing information · 2348f06e-8004-4040-832e-e9e86a39f905 · read 2026-08-30
On people who are breastfeeding, the label states: “Risk Summary There is no information regarding the presence of caplacizumab-yhdp in human milk, the effects on the breastfed child or the effects on milk production.”
US prescribing information · 2348f06e-8004-4040-832e-e9e86a39f905 · read 2026-08-30
On people with reduced liver function, the label states: “No formal studies with CABLIVI have been conducted in patients with severe acute or chronic hepatic impairment and no data regarding the use of CABLIVI in these populations are available.”
US prescribing information · 2348f06e-8004-4040-832e-e9e86a39f905 · read 2026-08-30
Where the result stopped carrying
Relapse followed withdrawal in eight phase 2 patients within a month, seven with unresolved ADAMTS13 deficiency — the drug suppresses the disease without treating it
Bleeding was substantially more common on treatment in both trials, and life-threatening and fatal bleeding has been reported since approval
The primary endpoint of the pivotal trial was met by a margin most clinicians would not be able to observe at the bedside
This is a scope explorer, not a diagnosis engine.
It shows who was studied so you can see whether people similar to you were included.
RNAWiki cannot tell whether a study fits you. It can show who was in it.
What it would be like to take◇Read from sources, not yet reviewed
Why it might seem to do nothing
A real effect and a noticed effect are different things. These are the recorded reasons the two come apart.
It was studied in different people
The people in the studies were not much like the reader.
On this record: Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.
The evidence may simply be wrong
Small early studies often do not hold up.
On this record: RNAWiki has not yet published a reviewed conclusion for this use.
Other reasons RNAWiki checked and found nothing for (11)
It was studied for a different goal
The studies measured something else entirely. Nothing in this record points to this reason.
A different form was studied
The studied form is not the form on the shelf. Nothing in this record points to this reason.
There was nothing to correct
Where a level is already normal, topping it up may change nothing. Nothing in this record points to this reason.
Something else had to happen too
In the studies it was paired with training, a diet or another treatment. Nothing in this record points to this reason.
The change is too small to feel
A real change can still sit below what a person notices. Nothing in this record points to this reason.
Day-to-day swing hides it
Sleep, food, stress and time of day move most numbers more than this would. Nothing in this record points to this reason.
Not enough time yet
The studies ran longer than the person has waited. Nothing in this record points to this reason.
It was not taken as studied
Missed days change the result, and studies count them. Nothing in this record points to this reason.
Something else changed at the same time
Two changes at once cannot be told apart afterwards. Nothing in this record points to this reason.
The product may not be what it says
Contents of a sold product are not always what the label states. Nothing in this record points to this reason.
No recorded reason
RNAWiki has nothing stored that would explain it. Nothing in this record points to this reason.
None of these is a reason to take more. Taking more is not a step this page ever suggests.
What it would be like to take◇Read from sources, not yet reviewed
What taking it involves
The recorded facts about getting hold of it and using it. Nothing here is a suggestion about what you should do.
How it is supplied
Given by a clinician
❝ Quoted from a source
Where this came from
Copied from a source RNAWiki stored, with the source named.
Read from the recorded approval status.
No source is stored against this line.
Form and route
Intravenous loading dose followed by daily subcutaneous injection
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
The form and route recorded on this substance.
No source is stored against this line.
Who oversees it
Professional supervision is normally required. It is a prescription or clinician-administered medicine where it is approved.
❝ Quoted from a source
Where this came from
Copied from a source RNAWiki stored, with the source named.
The identity record classes it as Monoclonal Antibody (mAb).
No source is stored against this line.
What is in the pack
A lyophilised powder in single-dose vials delivering 11 mg, reconstituted with 1 mL of sterile water. The first dose is given intravenously for immediate effect and subsequent doses subcutaneously once daily, continuing through plasma exchange and for a period afterwards. The daily schedule is a direct consequence of the molecule’s size: at 28 kDa it is cleared renally rather than recycled like a full antibody.
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
Recorded notes on how this is sold and what that means for what is in the pack.
No source is stored against this line.
Where it is registered
Regulatory records are listed in the technical disclosure at the foot of this page.
# Counted from records
Where this came from
A count of rows RNAWiki holds. It describes our records, not your body.
Register entries are stored per jurisdiction and shown with their dates.
No source is stored against this line.
Why people stop
Not recorded.
∅ Nothing recorded
Where this came from
RNAWiki holds nothing here and says so rather than guessing.
No record of why people stopped taking it is stored for this substance.
No source is stored against this line.
What it would be like to take◇Read from sources, not yet reviewed
What can go wrong
Sorted by where each line came from. A regulator's label and a report somebody sent in are not the same kind of fact.
·Worth asking a clinician aboutWritten into the record from the studies named on this page
No boxed warning, but bleeding is the defining risk. Bleeding events occurred in approximately 58% of treated patients against 43% on placebo, with severe epistaxis, gingival bleeding, upper gastrointestinal haemorrhage and metrorrhagia each reported in 1%. In the postmarketing setting, life-threatening and fatal bleeding has been reported. Risk is increased by underlying coagulopathy and by concomitant antiplatelet agents, thrombolytics, heparin or anticoagulants, which the label directs be avoided. Treatment should be interrupted for clinically significant bleeding and withheld for seven days before elective surgery, dental work or other invasive procedures. Von Willebrand factor concentrate may be given to correct haemostasis rapidly.
Nobody counted how many people took this and were fine, so this cannot be turned into a rate.
HERCULES — caplacizumab in acquired thrombotic thrombocytopenic purpura (NCT02553317) · a recorded source, not a stored snapshot
Over a long time. No completed tested study window is recorded, so long-term effects are not established by the registry record.
Groups the studies covered thinly. Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.
What is missing or unclear◇Read from sources, not yet reviewed
Does the exact form matter?
Evidence belongs to the exact thing that was tested. A different salt, a different mixture or a different preparation is a different question.
The form that was studied
Intravenous loading dose followed by daily subcutaneous injection
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
The form used in the studies cited on this page.
No source is stored against this line.
What is sold
The first dose is given intravenously for immediate effect and subsequent doses subcutaneously once daily, continuing through plasma exchange and for a period afterwards. The daily schedule is a direct consequence of the molecule’s size: at 28 kDa it is cleared renally rather than recycled like a full antibody.
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
Recorded notes on which forms are sold and how they compare.
No source is stored against this line.
What is recorded as being sold
1 product lists this as an active ingredient in the United States drug directory. 1 of them contain it and nothing else.
FDA National Drug Code directory · 68225-256 · read 2026-08-29
They are sold as injection, powder, lyophilized, for solution.
FDA National Drug Code directory · 68225-256 · read 2026-08-29
1 published label names it as an active ingredient. 1 of them describe this substance alone, which is where its own label text on this page comes from.
US prescribing information · 2348f06e-8004-4040-832e-e9e86a39f905 · read 2026-08-29
Those labels are classed as human prescription drug.
US prescribing information · 2348f06e-8004-4040-832e-e9e86a39f905 · read 2026-08-29
Evidence carries across two names for one substance. It does not carry across a salt, a mirror form or a mixture.
What it would be like to take◇Read from sources, not yet reviewed
What you could measure
This one is decided with a clinician, so this section holds questions to ask rather than a plan to run.
Self-experiment planning is not offered for a prescription or clinician-supervised medicine. The questions below are for a clinician or pharmacist.
Questions worth asking
Which of the trials of Caplacizumab studied people like me?
What was measured, and for how long?
Was the result a laboratory value or a health outcome?
What would we watch for, and when would we stop?
Tracking can show whether something changed for you. It cannot show what caused it.
RNAWiki records evidence. It does not say whether this substance is right for you.
What is missing or unclear◇Read from sources, not yet reviewed
Claims that go past the evidence
Things said about this substance that sound reasonable, and the exact step that is missing between the evidence and the claim.
✗Goes past the evidence
That the drug reduces mortality — four deaths occurred across 145 randomised patients in the pivotal trial and six across both trials, which cannot support any survival claim
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
✗Goes past the evidence
That a composite endpoint containing death demonstrates an effect on death; the composite moved because recurrence moved
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
✗Goes past the evidence
That the licensed primary endpoint, a four-and-a-half-hour median gain in platelet recovery, is the clinical reason to use the drug
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
✗Goes past the evidence
That the price reflects a cost of production, for a 28 kDa non-glycosylated fragment expressed in bacteria
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
What is missing or unclear◇Read from sources, not yet reviewed
What nobody knows yet
Open questions, each with why it is open and what would close it.
How much did people take in the studies?
The sources RNAWiki checked hold nothing for this field.
Why it matters. A result belongs to an amount. Without the amount the result floats free.
What would answer it
A stored source that records it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Missing populations
Which groups were under-represented in the studies has not been recorded.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Missing long-term data
No completed tested study window is recorded.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
No reviewed conclusion
RNAWiki has not yet published a reviewed conclusion for this use.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Missing interaction studies
No interaction was found in the registers checked. Not finding one is not the same as showing there is none.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Formulation uncertainty
Several salts, forms or products of Caplacizumab are recorded. Results from one form may not transfer to another.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Mechanism not reviewed
No reviewed mechanism story exists for this substance.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
What happened in people◇Read from sources, not yet reviewed
Check any of this yourself
Every line above traced back to the study it came from. This is the technical layer, and the vocabulary changes here.
Every line above can be traced to the study named beside it. Follow the link and read it.
The primary endpoint was won by about four and a half hours
In plain words
The trial’s main measurement was how long it took the platelet count to come back to normal. On caplacizumab it took 2.69 days; on placebo, 2.88. That difference is statistically significant and about four and a half hours long.
What was measured
Median time to normalisation of the platelet count, with discontinuation of daily plasma exchange within 5 days thereafter
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
HERCULES randomised 145 patients with acquired thrombotic thrombocytopenic purpura to caplacizumab or placebo during plasma exchange and for 30 days afterwards. The primary outcome was time to normalisation of the platelet count with discontinuation of daily plasma exchange within five days thereafter. Median time to normalisation was 2.69 days (95% CI 1.89 to 2.83) against 2.88 days (95% CI 2.68 to 3.56), p=0.01, with patients on caplacizumab 1.55 times as likely to normalise. A median difference of 0.19 days is roughly four and a half hours. Whether that endpoint should ever have been the primary one is the central editorial question about this trial: the case for the drug rests almost entirely on secondary outcomes, which is the reverse of how a pivotal trial is meant to read.
Written into the record, not signed off as a reviewed claim
The composite of death, recurrence and thrombosis fell from 49% to 12%
In plain words
The secondary outcome that actually matters combined TTP-related death, the disease coming back, and clots. It happened to 49% of the placebo group and 12% of the caplacizumab group.
What was measured
Composite of TTP-related death, recurrence of TTP or thromboembolic event during the treatment period
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The key secondary composite of TTP-related death, recurrence of TTP or a thromboembolic event during the treatment period occurred in 12% of the caplacizumab group against 49% of the placebo group, a 74% relative reduction (p<0.001). Recurrence at any point during the trial was 12% against 38%, a 67% reduction (p<0.001). Refractory disease developed in no caplacizumab patients and three placebo patients. Patients on caplacizumab required fewer plasma exchange procedures and had shorter hospital stays. The composite is heavily weighted by recurrence, which is the most frequent of its three components, so most of the apparent effect on a composite that includes death is in fact an effect on relapse.
Written into the record, not signed off as a reviewed claim
Four deaths in the whole trial is not a mortality result
In plain words
Three placebo patients died during treatment and one caplacizumab patient died afterwards, of a stroke. That is the entire mortality dataset. No trial of this drug has been sized to detect a survival difference.
What was measured
All deaths reported across the two randomised trials, 220 patients in total
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
HERCULES reports three deaths in the placebo group during the trial treatment period and one death in the caplacizumab group, from cerebral ischaemia after the end of the treatment period. The phase 2 TITAN trial, with 75 patients, reports two deaths in the placebo group and none on caplacizumab. Across both randomised trials the total is six deaths in 220 patients. Acquired thrombotic thrombocytopenic purpura at modern standards of care has a mortality of roughly 10 to 20%, and detecting a halving of that with any confidence would require several hundred patients per arm in a disease with an incidence of a few cases per million per year. The absence of a mortality trial is a structural feature of a rare disease, not an oversight — but it means the survival claim frequently attached to this drug is not something either trial measured.
Written into the record, not signed off as a reviewed claim
Stop it before the autoimmunity is treated and the disease comes straight back
In plain words
In the phase 2 trial, eight patients relapsed within a month of stopping the drug, and seven of those still had almost no ADAMTS13 activity. The drug had been holding the disease down without touching its cause.
What was measured
Relapses in the first month after stopping study drug, and ADAMTS13 activity in those patients
Effect estimate
No reviewed effect estimate exists for this record.
Limits
This entry records a failure.
From the source
In TITAN, 75 patients were randomised to subcutaneous caplacizumab or placebo during plasma exchange and for 30 days afterwards. Time to response was 39% shorter on caplacizumab (p=0.005) and exacerbations occurred in 3 patients against 11. Eight patients in the caplacizumab group relapsed in the first month after stopping the study drug, of whom seven had ADAMTS13 activity that remained below 10% — which the investigators identify as unresolved autoimmune activity. This is the defining limitation of the mechanism: blocking platelet adhesion suppresses every manifestation of the disease while the autoantibody against ADAMTS13 persists untouched, so the drug both masks the disease and defers it. Practice has adapted by monitoring ADAMTS13 recovery before stopping, which is a change in how the drug is used derived directly from this finding.
Written into the record, not signed off as a reviewed claim
It makes people bleed, and after approval some of that bleeding was fatal
In plain words
Bleeding from the nose, gums and gut was reported in 65% of patients on caplacizumab against 48% on placebo. Since approval, life-threatening and fatal bleeding has been reported.
What was measured
Incidence of bleeding adverse events on caplacizumab against placebo, and postmarketing reports of fatal bleeding
Effect estimate
No reviewed effect estimate exists for this record.
Limits
This entry records a failure.
From the source
The most common adverse event in HERCULES was mucocutaneous bleeding, in 65% of the caplacizumab group against 48% on placebo; in TITAN, bleeding-related adverse events occurred in 54% against 38%. The label reports bleeding events in approximately 58% against 43%, with severe reactions of epistaxis, gingival bleeding, upper gastrointestinal haemorrhage and metrorrhagia each in 1% of subjects, and states that in the postmarketing setting cases of life-threatening and fatal bleeding have been reported. Risk is increased by underlying coagulopathy and by concomitant antiplatelet agents, thrombolytics, heparin or anticoagulants, all of which the label directs be avoided. The drug is to be withheld seven days before elective surgery or dental procedures, and von Willebrand factor concentrate can be given to correct haemostasis rapidly — which is the closest thing this drug has to an antidote.
Written into the record, not signed off as a reviewed claim
Two hundred thousand dollars a course, for a 28 kDa bacterial protein
In plain words
The average Medicaid claim for caplacizumab in 2023 was just over US$200,000. The molecule is a small antibody fragment grown in ordinary bacteria, which is among the least demanding ways to make a biologic.
What was measured
Average Medicaid spending per claim and per dosage unit in 2023, against the labelled manufacturing description
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
CMS Medicaid data for 2023 record 109 claims and US$21,847,632.73 of spending on Cablivi, an average of US$200,436.99 per claim at US$7,921.55 per dosage unit. The product is a 28 kDa fragment of two identical humanised single variable domains joined by a three-alanine linker, produced in Escherichia coli — requiring no glycosylation, no Fc assembly, no mammalian cell culture and no chain pairing. Nothing in the manufacturing description explains the price, and no published cost-of-production study covers it, which is why `synthesisCostPerDose` on this page is empty rather than estimated. No cited cost-of-production evidence ties that price to the manufacturing steps described above.
Source
CMS Medicaid Spending by Drug, 2023 reporting year — Cablivi; CABLIVI prescribing information section 11 Description
Role in the trial
Not matched to a registered study
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Audit mark
caution
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Where else this substance is registered
FDA substance identifier (UNII)
2R27AB6766
CAS registry number
915810-67-2
ChEMBL
CHEMBL2109624
WHO international nonproprietary name list entry
9511
RxNorm concept
2110605
EMA substance identifier
100000166854
DrugBank
DB06081
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The identity record classes it as Monoclonal Antibody (mAb).
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How this medicine reached us
Kept near the foot of the page. A historical event moves up only when it changes something about this substance today.
What the approval register records
The earliest marketing start date recorded for a listed product is 20190206.
FDA National Drug Code directory · 68225-256 · read 2026-08-29
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The older medicine-wide conclusion held in this record
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A two-domain antibody fragment that clamps the A1 domain of von Willebrand factor so platelets cannot be dragged onto it, which won its pivotal trial’s primary endpoint by a median of four and a half hours — 2.69 days to platelet normalisation against 2.88 — while cutting a composite of death, recurrence and thrombosis from 49% to 12%, raising mucocutaneous bleeding from 48% to 65%, and leaving relapse to follow within weeks in patients whose underlying enzyme deficiency had not yet been corrected.
Recorded evidence blocks (7)
Q1
On the Caplacizumab label: indicated for what?
"CABLIVI is indicated for the treatment of adult and pediatric patients 12 years of age and older with acquired thrombotic thrombocytopenic purpura (aTTP), in combination with plasma exchange and immunosuppressive therapy. CABLIVI is a von Willebrand factor (vWF)-directed antibody fragment indicated for the treatment…": indications and usage on Caplacizumab's label. DailyMed label · 2348f06e-8004-4040-832e-e9e86a39f905 · 2026-04-24
Q2
13 registered trials of Caplacizumab — at which phases?
"Recommendations of the independent oversight committee."; 1 of 13 registered studies
Show the evidence
TrialNCT04720261
terminated; "Recommendations of the independent oversight committee."
recorded 2026-09-01 · last checked 2026-09-04
Q4
Which 3 trials of Caplacizumab posted no result?
Posted no result
3 of 3 completed trials
Registrations
NCT01020383, NCT04074187 and NCT05263193
Completion dates
oldest 2012-03; newest 2022-10-28
Show the evidence
Trial
NCT01020383
2012-03
NCT04074187
2021-05-19
NCT05263193
2022-10-28
Q5
At the median, Caplacizumab's trials enrolled 75 people — anything larger?
Median enrolment
75
Largest enrolment
364
Registered trials counted
13
Q6
What do 148 spontaneous reports say about Caplacizumab — and not say?
These are reports people sent to a regulator. They do not show the medicine caused the reaction. Nobody counted how many people took the medicine and reported nothing. The same event can be reported more than once, and many reports are incomplete. News coverage, lawsuits and new warnings change how often people report. A count is not a rate and not a risk.
Caplacizumab appears in spontaneous reports to regulators. Across the 10 most-reported reaction terms, 148 reaction mentions were counted: platelet count decreased 32; adamts13 activity decreased 20; thrombotic thrombocytopenic purpura 20; condition aggravated 15. FAERS via Open Targets · CHEMBL2109624 · 2026-06-24
Show the evidence
platelet count decreased
32
adamts13 activity decreased
20
thrombotic thrombocytopenic purpura
20
condition aggravated
15
epistaxis
13
disease recurrence
10
4 more recorded rows
gastrointestinal haemorrhage
10
haemorrhage
10
thrombocytopenia
10
contusion
8
recorded 2026-06-24 · last checked 2026-09-04
Q7
Which 10 reactions does Caplacizumab's label not list?
ChEMBL 37 — CC BY-SA 3.0 Unported · ChEMBL ATC CC BY-SA · ClinicalTrials.gov — US Government work · Open Targets 26.06 — CC0 · mixed register set; per-register licences in docs/specs/corpus-20k-sources.md · openFDA / DailyMed — US Government work
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